1. Technical Field
Embodiments of the present invention relates to an image forming apparatus employing electrophotography.
2. Related Art
In current image forming apparatuses employing the electrophotographic method, some can use a special toner other than so-called CMYK process color toners processing colors of cyan (C), magenta (M), yellow (Y), and black (K). Such an image forming apparatus is configured such that either an image forming station for the special toner is included in addition to the four CMYK image forming stations or the image forming station for one of the process color toners is used for the special toner.
One of the examples of the special toner includes clear toner, as also called transparent toner, colorless toner, achromatic color, pigment-less toner, and the like. The clear toner is overlaid on part or all of the colored printed matter and the gloss adjusted thereby, thereby creating high value-added printed matter.
Other examples of special toner include red (R) toner, green (G) toner, and blue (B) toner. Use of those colors enables high quality reproduction of colors that cannot be reproduced using only the CMYK process color toners. There are many types of special colors other than the above.
In using the above special toner, there are cases in which a user replaces the toner of the image forming station of the image forming apparatus. One case is that the user replaces the process color toner with the special toner, and the other case is that the user replaces the special toner with the process color toner, or otherwise, from one type of special toner to another type of special toner, and from one process color toner to another process color toner. In the replacement of different types of toner, undue contamination occurs due to the mixing of colors caused by the replacement of different types of toner. Further, there is a possibility that an abnormal image is produced or the image forming unit is damaged.
To cope with such a problem, some image forming apparatuses can produce an image by overlaying color toner images including the special color in a desired order to form a color image, by replacing CMYK toner cartridges with a cartridge of the special color. Such image forming apparatuses are configured such that the image formation is enabled by overlaying the color toner images including an image of the special toner in the desired order by simply replacing the CMYK toner cartridges with the special color toner cartridge; however, color mixing of the different types of toner due to human error that replaces the toner cannot be prevented.